The purpose of this proposed research is to explore the possibility that primary tooth allografts between H-2 identical multiple-non-H-2 disparate mice create an immunological environment that would favor the survival of subsequent donor strain teeth and perhaps other tissues and organs as well. The objectives of the study are as follows: 1) to develop and refine in vitro correlates of the tooth-generated suppressor systems; 2) to determine if suppression is mediated by serum factors as well as spleen cells; 3) to characterize the kinetics of the suppressive response; 4) to determine the dose and antigenic form which produces the maximum suppression; 5) to test the in vivo effects of tooth-induced suppression on subsequent donor allografts; and 6) to test the genetic limits of tooth-induced supression. The following methods will be employed: 1. Short (4 hour) and long (20 hours) incubation 51Cr-release assays which use donor-strain tumor cells and normal blast cells as targets. 2. Lymphocyte transformation assays using the mitogens PHA and LPS as well as specific donor-strain and unrelated-strain lymphocytes as stimulators. 3. Effect of normal and immune sera on recipient-strain anti-donor responses in vitro & in vivo. 4. The in vivo evaluation of transplanted organs such as skin and heterotopic hearts. 5. The histologic evaluation of transplanted organs such as teeth, bone, and skin.